1. Field of the Invention
The present invention relates generally to waste treatment, and in particular to a method of organic waste treatment.
2. Description of Related Art
The livestock industry has seen a gradual progression from a large number of smaller operations to a smaller number of larger operations, each confining large numbers of animals in a relatively small area. This trend has had a tendency to increase profits, as well as to increase the concentration of animal waste. Last year about sixty-four million tons of animal waste were generated in the United States from confined livestock.
Currently, the most common type of livestock feeding facility has a flooring grate or pit which allows animal manure to fall away from the animals themselves into a holding area. Water is then used to periodically flush the manure from the holding area, thereby forming a waste slurry. The slurry is then piped into a holding lagoon where much of the solid waste precipitates into a sludge at the bottom of the lagoon or pit.
Unfortunately, there are several drawbacks to the aforementioned method. While there is bacteria present in the lagoons capable of digesting the accumulating sludge, this anaerobic digestion is a slow process and is ordinarily not efficient enough to prevent the buildup of sludge on the bottom of the lagoon or pit. Lagoons often fill to capacity in short order, which tends to limit their effectiveness as holding areas.
Many of the bacteria present in lagoons tend to produce noxious odors as they break down the sludge. These odors are especially troublesome and may be considered a nuisance when the lagoons are located near populated areas. Many states require large buffer zones around waste lagoons.
When lagoons or pits fill, the sludge is spread over surrounding fields as fertilizer. Due to the anaerobic bacteria's inability to completely digest the sludge, unacceptably high levels of phosphorous, nitrogen and other nutrients are often present. These nutrients build up into high residual concentrations in the soil and can leach directly into groundwater or run-off into surface waters. Nutrient pollution has been inked to low oxygen concentrations in surface waters and fish kills from the nutrient induced hyper-reproduction of dinoflagellates.
The related art shows several attempts to address the problems inherent with the abovementioned method of manure disposal. For example:
U.S. Pat. Publication No. 2002/0030012, published Mar. 14, 2002, discloses a process to create a treated recycle stream through pre-treatment and solids separation for reuse in animal feeding operations. The method disclosed in the publication differs from the present invention in that the present invention is much simpler in design and results in an end product consisting of a soil nutrient rather, than a protein supplement.
U.S. Pat. No. 3,701,727, issued to Kormanik, and U.S. Pat. No. 3,893,924, issued to Le Compte, Jr. et al., disclose different methods of aerating waste lagoons to encourage aerobic consumption of organic waste. Neither of these methods involves the separation of the liquid and solid components of organic waste, as does the present invention.
U.S. Pat. No. 3,973,043, issued to Lynn, discloses a method of transforming feedlot animal wastes into useful materials. The process involves using anaerobic fermentation of a waste slurry to produce and capture methane with a following aerobic fermentation step to further reduce the waste slurry into animal feed. This method differs from the present invention in, among other ways, that it does not produce soil nutrients as an end product.
U.S. Pat. No. 5,282,879, issued to Baccarani, discloses a continuous process for the preparation of fertilizers from animal waste. This method differs from the present invention in that it uses non-naturally occurring chemicals, such as nitric acid and calcium hydroxide, to break down the animal waste.
U.S. Pat. No. 5,627,069, issued to Powlen, discloses methods and compositions for treating on-site animal waste pits in order to soften the fluidized hardened solid wastes found therein. The methods and compositions involve the use of Lactobacillus bacteria and nitrogen fixing bacteria. The '069 patent differs from the present invention in that the '069 invention is intended to break up encrusted solids on the bottom of a waste lagoon rather than to breakdown separated solids into soil nutrients.
U.S. Pat. No. 6,395,174, issued to Teran et al., discloses an apparatus and method for treating waste lagoons. The method involves aeration of the lagoon and the insertion of bacteria specialized to digest the particular type of waste present therein. The '174 patent differs from the present invention in that it does not show a step of injecting bacteria into dewatered waste solids.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.